The purpose of this project is to study the interaction of normal and metastatic tumor cells with molecular components of the extracellular matrix. Particular emphasis has been directed towards understanding the role of the laminin molecular and its various domains in promoting or inhibiting the adhesion of cells to the collagenous component of the subendothelial basement membrane. Additional studies include development of a reconstituted basement membrane to be used to test the metastatic potential of tumor cells. Development of this assay system also allows for selection of highly metastatic cell varients from a heterogeneous tumor cell population. Further emphasis has been placed on understanding the roles of fibronectin, laminin and types I and IV collagen in directing cellular differentiation of both normal and neoplastic cells. A second direction of this project is concerned with the reattachment of periodontal connective tissue to tooth root surfaces which have been scaled partially demineralized through the use of citric acid application and then pretreated with fibronectin isolated from the patients serum.